I. Field of the Present Invention
The present invention relates generally to meters for measuring the flow rate of fluid in a fluid system, and more particularly to such a meter having perceptible indicators for displaying an indication of fluid characteristics related to the temperature and flow rate of the fluid.
II. Description of the Prior Art
There are many types of previously known flow meters which provide a visual indication of the flow rate of a fluid in a fluid system. For example, in a moving vane type flow meter, a vane is displaced and oriented in a predetermined position corresponding to the flow rate of the fluid passing through the meter. The vane may be linked to an arm extending across the face of a scale so that the position of the arm on the scale provides a visible indication of the flow rate of the fluid. Quite often, the indicator is positioned outwardly of the flow meter so that the indicator is visible from the exterior of the flow meter housing. As a result, the linkage between the vane acted upon by the fluid and the indicator can add a substantial amount of weight and inertia to the vane mechanism, thus reducing the efficiency and accuracy of the reading provided by the indicator.
Of course, other indicator means may also be external to the flow meter such as a digital display device. However, such devices are substantially more complex and often more expensive than simple mechanical linkages and indicators. In any event, previously known flow meters are of limited use in that they convey no information as to other characteristics of the fluid such as temperature, or characteristics of a fluid which may change in response to changes in temperature or flow rate.
In addition, although there are known means for measuring the temperature of a fluid, previously known thermometers are not well adapted for use with flow meters. As a result, the empirical data which is provided by the previously known flow rate meters and temperature indicators must be analyzed and calculated according to standard material property relationships in order to obtain information about other characteristics of the fluid in the system. For example, in order to establish the net heat flow rate between two points in a fluid system, substantial calculations must be performed utilizing the data from the previously known flow meters and temperature indicators. Similarly, when the viscosity of the fluid is affected by changes in temperature of the fluid, it may be necessary to perform complex calculations to determine the viscosity of the fluid under existing fluid system conditions. While such calculations can be handled by trained engineers, such a process can be time consuming and may not be easily handled by untrained mechanics.
Although it may also be possible to utilize a computer in processing the information, such a system is extremely complex and prohibitively expensive, especially for small fluid systems. In any event, the previously known flow rate meters do not provide a visual indication of the tempertaure and flow rate in a manner which readily displays other desired fluid flow characteristics, or in a manner which would be readily understood by unskilled technicians and others without substantial data processing.